Yeast Investigation

Daniel Gillespie 11F Biology Coursework SC1 Introduction to yeast Yeast are unicellular fungi. It has been around for along time and has been involved in the making of bread, wine and other materials for man. Now yeast is used in many different industries for its fermentation properties. During this process in the industries the yeast is the waste product and is usually used for animal food or birdseeds. However the alcohol is the valuable product in the industry. Yeast has been a major material to man for a long time and is now a very expensive and profitable material for businesses and industries. The yeast respires to produce energy. When it does respire it produces and needs products and waste products, these are shown in the word equation below. To control this reaction the yeast has an enzyme; this enzyme is called zymase. Enzymes are used to control the speed and the rate of the respiration in the yeast, it changes the rate and speed by the environmental surroundings it is put in. glucose -----yeast---> ethanol + carbon dioxide + energy (210kj) C6H12O6 -----yeast---> 2C2H5OH + CO2 The reaction shown above is also called Fermentation. Fermentation is used in the brewing industry and the picture below shows how they ferment the sugar (glucose) in the yeast to make alcohol. Fermentation is the break down of sugars by using yeast

  • Word count: 4412
  • Level: GCSE
  • Subject: Science
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Why Does the Colour Leak Out of Cooked Beetroot?

Why Does the Colour Leak out of Cooked Beetroot? Aim: To investigate the effect of temperature on membrane structure. Hypothesis: I think that as the temperature increases the pigment contained within the cells will be released as the membrane breaks down. The pigments in beetroot cells are called betalin pigments. To extract the pigment, the cell membranes must be disrupted. This can be done by heat shock, by detergents or by solvents (e.g. ethanol or acidified methanol). Thin slices have a larger surface area and so leak more pigment; freezing the beetroot first bursts the cell membranes and kills the cells, thus allowing the pigment to be extracted much more quickly. When you heat a beetroot, you disrupt the cell membranes. A biological membrane is made of a so-called phospholipid bilayer. These are formed because the phospholipids that make it up have a polar "water-loving" (hydrophyllic) head and a "water-hating" (hydrophobic) tail. The tails pack together, exposing only the polar heads to the water. When you heat something you give it energy. Molecules start to spin and vibrate faster. The water will expand too. This will have a disruptive effect on any membrane in its way. To make things worse, lipids become more fluid as temperature goes up (so the membranes become more fragile. Proteins are formed of coiled and folded strings of amino-acids, held together by

  • Word count: 1408
  • Level: GCSE
  • Subject: Science
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Why does the colour leak out of cooked beetroot?

Why does the colour leak out of cooked beetroot? Hypothesis: Increasing the temperature of water baths surrounding sections of beetroot will cause the partially permeable membrane of the vacuole to become less stable, causing it to lose control of transport across, and allow betalains, red pigments, to pass out of the tonoplast and cause the beetroot to lose colour. When the distilled water containing the beetroot is tested, it will absorb much more light because the pigment leaked into it will cause it to become opaque. As we increase the temperature, so will the amount of pigments released increase, in a directly proportionate positive correlation. Aim: To find out if increasing the temperature of beetroot samples will affect the containment of pigment. Method: . We placed 8 slices of previously prepared 1cm³ beetroot into boiling tubes containing 5cm³ distilled water. 2. These we placed into water baths at temperatures of 0°C, 10°C, 20°C, 30°C, 40°C, 50°C and 6O°C, leaving them for thirty minutes to ensure that the beetroot and water reached the required temperature. For the water baths we used a selection of ice, salt, and boiling water to reach the desired temperature. 3. We then removed the beetroot sections from the boiling tubes, and shook the water and pigment solution to disperse the dye, and break any ice where appropriate. 4. From each boiling

  • Word count: 1430
  • Level: GCSE
  • Subject: Science
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